Views of the U.S. National Academies of Sciences, Engineering, and Medicine on Agenda Items of Interest to the Science Services at the World Radiocommunication Conference 2019 (2017) / Chapter Skim
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1 Introduction
1 Introduction
Pages 1-11
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Changing the band of operation is not always viable, particularly for scientists, who in many cases must observe at specific frequency bands, which can be dictated in remote sensing by the electro agnetic properties of Earth parameters, such as sea m surface temperature, sea salinity, surface winds, and soil moisture; or, in the case of radio astronomers, the transition frequencies of atoms and molecules, which are established by the laws of physics and chemistry. OTE: Portions of this text are taken from National Research Council, Views of the N NAS and NAE on Agenda Items at the World Radiocommunication Conference 2015, The National Academies Press, Washington, D.C., 2013.
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Passive services use receivers to measure natural radio frequency emissions from ocean, land, and atmosphere phenomena such as hurricanes or, in the case of radio astronomy, cosmic sources such as solar system objects, stars, and the medium between stars, galaxies, and other celestial bodies. RAS, as defined in the radio regulations, is always a passive service.
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Recommendations ITU-R RA.769 and ITU-R RS.2017 contain the threshold levels of interference that are deemed detrimental to the use of the radio spectrum by the passive scientific services. Scientific users understand the need to share the spectrum between active and passive users, but it is important to note that some sharing techniques that work for active services do not necessarily work for passive uses.
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Agenda items are typically very specific and propose substantial changes to the use of the spectrum that can have a significant impact on services. Because more than 95 percent of spectrum allocations below 3 GHz are for active uses of the spectrum, it is critical for vulnerable passive services to participate in the process and express their concerns about potential adverse effects on their operations.3 To ensure their continued ability to access the radio spectrum for scientific purposes, scientists must participate in the discussions leading up to WRC-19, scheduled to be held in November 2019 in Geneva, Switzerland.
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A more complete view of both the scientific uses and the frequency allocations can be found in the Handbook of Frequency Allocations and Spectrum Protection for Scientific Uses: Second Edition.4 EARTH EXPLORATION-SATELLITE SERVICE Satellite remote sensing is a uniquely valuable resource for monitoring the global atmosphere, land, and oceans. Microwave remote sensing from space presents a global view, vital for obtaining atmospheric and surface data for the entire planet.
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by Earth stations in motion communicating with geostationary space stations in the fixed-satellite service and take appropriate action, in accordance with Resolution 158 (WRC-15) 1.6 To consider the development of a regulatory framework for non GSO FSS satellite systems that may operate in the frequency bands 37.5-39.5 GHz (space-to-Earth)
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, in the frequency bands between 5150 MHz and 5925 MHz, and take the appropriate regulatory actions, including additional spectrum allocations to the mobile service, in accordance with Resolution 239 (WRC-15) WRC-23 2 On the basis of proposals from administrations and the Report of the Conference Preparatory Meeting, and taking account of the results of WRC-19, to consider and take appropriate action in respect of the following items: 2.2 To conduct, and complete in time for WRC-23, studies for a possible new allocation to the Earth Exploration-Satellite Service (active)
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For many applications, satellite-based RF remote sensing represents the only available method of obtaining atmospheric and surface data for the entire planet. Major U.S.
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Measurements of radio spectral line emission have identified and characterized the birth sites of stars in the Milky Way, the processes by which stars slowly die, and the complex distribution and evolution of galaxies in the universe. Radio astronomy measurements discovered the cosmic microwave background (CMB)
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These include the following: optical mapping technology adapted for laser eye surgery; wireless networking technology; sensitive microwave receiving systems, including high-gain antennas and low-noise receivers; cancer therapy using knowledge obtained from observing black hole environments; time calibration for GPS; and wireless technology, including fast Fourier transform chips, solid-state oscillators, frequency multipliers, and cryogenics. Other examples include data correlation and recording technology and image restoraion tech t niques, among many others.
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Indeed, it is clear that all users, both passive and active, benefit from a clean spectrum. Thus, while radio astronomy facilities rely in part on geographic shielding and local designations of radio quiet zones to reduce sources of RFI, it is the shared responsibility of all users to assure effective use of the radio spectrum and to enable both active and passive services to coexist.
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